Chitosan is a non-toxic cationic copolymer of N-acetyl-D-glucosamine and D-glucosamine. Chitosan can form a complex with nucleic acid and, as a biocompatible and non-toxic polysaccharide, has been used as a DNA delivery vehicle to transfect cells. Much interest has been focused on using chitosan in non-viral delivery of nucleic acid due to the complexities and potential toxicity of the viral vector
A number of chitosan/DNA complexes, including complexes between modified chitosan and nucleic acids, have been examined in an attempt to identify compositions well suited for gene transfection. See, e.g., WO2010/088565; WO2008/082282. The complexes have been found to vary in, among other properties, solubility, propensity for aggregation, complex stability, particle size, ability to release DNA, and transfection efficiency.
Thus, there is a need for new compositions and methods for gene transfer in vivo with improved transfection efficiency. The compositions and methods described herein help meet these and other needs.